PushLocalFrame needs to return an ownership type

Author: jfirebaugh

include/jni/functions.hpp

@@ -114,13 +114,15 @@ namespace jni
        }
 
 
-    inline void PushLocalFrame(JNIEnv& env, jint capacity)
+    inline UniqueLocalFrame PushLocalFrame(JNIEnv& env, jint capacity)
        {
         CheckJavaExceptionThenErrorCode(env, env.PushLocalFrame(capacity));
+        return UniqueLocalFrame(&env, LocalFrameDeleter());
        }
 
-    inline jobject* PopLocalFrame(JNIEnv& env, jobject* result = nullptr)
+    inline jobject* PopLocalFrame(JNIEnv& env, UniqueLocalFrame&& frame, jobject* result = nullptr)
        {
+        frame.release();
         return CheckJavaException(env,
             Wrap<jobject*>(env.PopLocalFrame(Unwrap(result))));
        }

include/jni/ownership.hpp

@@ -6,6 +6,20 @@
 
 namespace jni
    {
+    struct LocalFrameDeleter
+       {
+        void operator()(JNIEnv* env) const
+           {
+            if (env)
+               {
+                env->PopLocalFrame(nullptr);
+               }
+           }
+       };
+
+    using UniqueLocalFrame = std::unique_ptr< JNIEnv, LocalFrameDeleter >;
+
+
     class GlobalRefDeleter
        {
         private: